Dueling opamp inputs

Circuit Break Podcast #79

Dueling OpAmp Inputs

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August 4, 2017, Episode #79

Stephen makes a peristaltic pump and Parker hacks his Jeeps turn signals for LEDs!
  • Parker
    • Article is lagging behind. Will be done on Friday, promise!
    • Rewiring the Jeep Turn signals. The old wiring was interesting.
      • The side marker bulb socket is isolated from ground. One bulb lead goes to the front marker parking lamp positive circuit. The other lead of the side marker is tied into the front marker turn signal positive circuit.
      • When the parking lights are on and the turn signal off, the side marker grounds through the front marker turn signal filament and illuminates the marker lamp.
      • When the turn signal flashes, it interrupts the ground and the marker will flash by dimming. The front marker gets brighter. So they alternate.
      • When the parking lights are off, the filament which the side marker grounds through is reversed. Thus they blink at the same time.
      • This works because of the wattage difference in the side marker and front marker. 4W for the side marker and 24W for the front. High wattage filament looks like a low resistance path to ground and the side marker doesn’t send enough current to turn them on.
      • Problem when you convert to LED. The system works great with LEDs as is. But because LEDs have a voltage drop, they create a little voltage on the turn signal line. This voltage isn’t enough to turn on the turn signal markers up front but it does turn on the indicators on the dash. ANNOYING!
      • Daniel Stern Lightning
      • Parker also experiences diode problem with voltage offset from ground. Punk-a$$ Diodes!
  • Stephen
    • Peristaltic pump design – looking into potentially adding this to his brew rig
      • Homebrew pump controlled in loop with proportional valves and flow meter
      • Control flow rate and through put
      • Skateboard ball bearings. A useful, and fancy fidget spinner
    • Craft Beer Pi
      • Going to get a Raspberry Pi programmed up this weekend
      • Wants to use the pump with their interface
    • DS18B20 temp sensor –
      • Have 5 coming in tomorrow
      • Power, ground, and 1 wire signal
      • 9-12 bits
      • -10 +85 Celsius
      • Plugs directly into raspberry pi without anything in between. Craft Beer Pi already has support!
      • Amazon Link
  • Pick Of the Week (POW)
  • Rapid Fire Opinion (RFO)
    • Should Stephen and Parker build an IoT of happiness for MacroFab?
    • Poll: Should we have a StarWars Xmas Special Part II? Link to the first Special.

Have an idea for a podcast episode? Maybe a question for Parker and Stephen? [Hit us up!](mailto: podcast@macrofab.com)

Did you enjoy this episode? Let us know in the comments below!

Figure 1: Schematic ripped from the Jeep’s service manual.

Figure 1: Schematic ripped from the Jeep’s service manual.

Figure 2: Simplified wiring diagram for the turn signals.

Figure 2: Simplified wiring diagram for the turn signals.

Figure 3: Stephen’s peristaltic pump! SOIC-8 for scale.

Figure 3: Stephen’s peristaltic pump! SOIC-8 for scale.

About the Hosts

Parker dillmann
  Parker Dillmann

Parker is an Electrical Engineer with backgrounds in Embedded System Design and Digital Signal Processing. He got his start in 2005 by hacking Nintendo consoles into portable gaming units. The following year he designed and produced an Atari 2600 video mod to allow the Atari to display a crisp, RF fuzz free picture on newer TVs. Over a thousand Atari video mods where produced by Parker from 2006 to 2011 and the mod is still made by other enthusiasts in the Atari community.

In 2006, Parker enrolled at The University of Texas at Austin as a Petroleum Engineer. After realizing electronics was his passion he switched majors in 2007 to Electrical and Computer Engineering. Following his previous background in making the Atari 2600 video mod, Parker decided to take more board layout classes and circuit design classes. Other areas of study include robotics, microcontroller theory and design, FPGA development with VHDL and Verilog, and image and signal processing with DSPs. In 2010, Parker won a Ti sponsored Launchpad programming and design contest that was held by the IEEE CS chapter at the University. Parker graduated with a BS in Electrical and Computer Engineering in the Spring of 2012.

In the Summer of 2012, Parker was hired on as an Electrical Engineer at Dynamic Perception to design and prototype new electronic products. Here, Parker learned about full product development cycles and honed his board layout skills. Seeing the difficulties in managing operations and FCC/CE compliance testing, Parker thought there had to be a better way for small electronic companies to get their product out in customer's hands.

Parker also runs the blog, longhornengineer.com, where he posts his personal projects, technical guides, and appnotes about board layout design and components.

Stephen Kraig
  Stephen Kraig

Stephen Kraig is a component engineer working in the aerospace industry. He has applied his electrical engineering knowledge in a variety of contexts previously, including oil and gas, contract manufacturing, audio electronic repair, and synthesizer design. A graduate of Texas A&M, Stephen has lived his adult life in the Houston, TX, and Denver, CO, areas.

Stephen has never said no to a project. From building guitar amps (starting when he was 17) to designing and building his own CNC table to fine-tuning the mineral composition of the water he uses to brew beer, he thrives on testing, experimentation, and problem-solving. Tune into the podcast to learn more about the wacky stuff Stephen gets up to.

Special thanks to whixr over at Tymkrs for the intro and outro!

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